Jude, we've embarked in NY several times, and I agree with Ron that it isn't always easy to predict how smoothly embarkation will be.
That said, I do have one piece of advice. NYC is such a marvelous port from which to leave that I urge you to stay out on deck as long as possible. As you head down the Hudson River, the Manhattan skyline will be to your left. Soon after passing the tip of Manhattan, move to the right side of the ship to have a spectacular view of the Statue of Liberty. Then, go up to the highest deck (if you are not there already) for an amazing trip under the Verrazano Bridge. Trust me, this is not to be missed.
I wish I were going too.